The weak nucleon axial-vector (FA) and vector (FV) form factors are determined from the momentum-transfer-squared (Q2) distributions using 2538-p and 1384-++ events. The data were obtained from 1 800 000 pictures taken in the BNL 7-foot deuterium-filled bubble chamber exposed to a wide-band neutrino beam with a mean energy E=1.6 GeV. In the framework of the conventional V-A theory with standard assumptions, the value obtained from the -p events for the axial-vector mass MA in the pure dipole parameterization is 1.070+0.040-0.045 GeV and from the -++ events is 1.28+0.08-0.10 GeV. These results are in good agreement with an earlier measurement from this experiment and other recent results. The reaction mechanisms for both processes are compared and found to be very similar. A two-parameter fit for the quasielastic reaction, using dipole forms for FV and FA yields MA=0.97-0.11+0.14 GeV and MV=0.89-0.07+0.04 GeV, which is in good agreement with the conserved-vector-current value of MV=0.84 GeV. Possible deviations from the standard assumptions are also discussed.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)